Fibreoptic views through the laryngeal mask and the intubating laryngeal mask.

BACKGROUND AND OBJECTIVE: The intubating laryngeal mask (intubating laryngeal mask airway) was designed to facilitate blind intubation. Its value as an adjunct to fibreoptic laryngoscopy has not been evaluated. This study compares the intubating laryngeal mask airway with the standard laryngeal mask airway as conduits for fibreoptic laryngoscopy. METHODS: The fibreoptic view of the laryngeal inlet was graded via both devices in 60 anaesthetized patients. The fibreoptic view through the intubating laryngeal mask airway was assessed after the central epiglottic elevator bar had been lifted out of the field of vision by an 8-mm Euromedical tracheal tube, which was inserted to a depth of 18 cm. The fibreoptic view from the aperture bars of the laryngeal mask was recorded. RESULTS: The vocal cords were viewed less frequently through the intubating laryngeal mask airway (52%) than through the laryngeal mask airway (92%) [difference = 40% (95% CI = 26% to 54%), P < 0.0001]. CONCLUSION: The view of the laryngeal inlet is better through the laryngeal mask airway than through a tracheal tube inserted to 18 cm in the intubating laryngeal mask.     

Supreme喉罩与i-gel喉罩用于俯卧位腰椎手术患者气道管理效果的比较

目的比较Supreme喉罩和i-gel喉罩用于俯卧位腰椎手术患者气道管理的效果。方法择期行俯卧位腰椎手术患者264例,采用随机数字表法将患者分为两组,每组132例。麻醉诱导后S组和I组分别置入Supreme喉罩和i-gel喉罩。记录喉罩置入次数、置入时间;记录仰卧位和俯卧位时的通气质量、气道峰压、气道密封压,并采用纤支镜观察喉罩位置,行喉罩对位分级;记录喉罩血染的发生情况;记录喉罩相关并发症的发生情况。结果 I组有1例患者于仰卧位时3次置入喉罩均失败,被排除。两组患者置入喉罩型号、置入时间、仰卧位和俯卧位气道峰压和纤支镜评级差异无统计学意义。与S组比较,I组喉罩尝试置入次数明显增多,俯卧位通气质量明显升高,俯卧位和仰卧位气道密封压明显升高(P0.01或P0.05)。两组患者喉罩相关并发症发生情况差异无统计学意义。结论俯卧位腰椎手术患者气道管理中,相比Supreme喉罩,i-gel喉罩置入难度较大,但具有更高的气道密封压。     

A randomised trial comparing the laryngeal mask airway Supreme™ with the laryngeal mask airway Unique™ in children

We conducted a randomised controlled trial comparing the laryngeal mask airway Supreme^? with the laryngeal mask airway Unique^? in children. Fifty children presenting for elective surgery were randomly assigned to receive either the laryngeal mask airway Supreme or laryngeal mask airway Unique. The outcomes measured were airway leak pressure, ease and time for insertion, insertion success rate, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement through the laryngeal mask airway Supreme, quality of airway during anaesthetic maintenance and complications. Median (IQR [range]) time to successful device placement was shorter with the laryngeal mask airway Unique, 14.5 [13.5–16.3 (10.0–23.6)] s than with the laryngeal mask airway Supreme, 17.4 [14.8–19.8 (11.5–29.2)] s; p = 0.007. Median (IQR [range]) airway leak pressures for the laryngeal mask airway Supreme and laryngeal mask airway Unique were 20 [16–21 (12–22)] cmH₂O and 15 [14–18 (10–24)] cmH₂O, respectively (p = 0.001). The incidence of gastric insufflation was lower with the laryngeal mask airway Supreme (zero vs six patients), p = 0.01. In conclusion, the laryngeal mask airway Supreme performed as well as the laryngeal mask airway Unique and is a useful alternative for airway maintenance, particularly in children who require evacuation of gastric contents during anaesthesia.     

Problema inusual con la mascarilla laríngea Supreme™. Caso del trimestre

A breast tumor was resected under general anesthesia. After induction, the airway was managed with a Supreme™ laryngeal mask airway device. The insertion of the laryngeal mask airway device, the insertion of the orogastric tube through the drain tube, as well as the mechanical ventilation, were very difficult from the beginning. On removing the laryngeal mask airway device to solve the problem, it was observed that the drain tube was broken, and the orogastric tube had passed into the anterior, laryngeal part of the device through the split. It was later found out that the laryngeal mask airway device, as well as the whole manufacturing batch, had suffered a design modification: the cuff was constructed with a softer material without reinforcement in the tip, and the drain tube had a heat-sealing defect that facilitated the break. The incident was reported to the local supplier and the manufacturer, and the defective batch of laryngeal mask airway devices was recalled. The incident was also reported to other hospitals via SENSAR, to warn other users of the potential dangers of the design modification in the Supreme™ laryngeal mask airway.     

The intubating laryngeal mask. Results of a multicentre trial with experience of 500 cases

A multicentre trial of the use of the intubating laryngeal mask was carried out at seven centres in the United Kingdom using the same agreed protocol. Lung ventilation followed by blind tracheal intubation through the intubating laryngeal mask was attempted on 500 ASA grade 1 and 2 patients. It was possible to insert the intubating laryngeal mask in all 500 cases. Ventilation via the intubating laryngeal mask was described as satisfactory in 475 (95%) cases, difficult in 20 (4%) cases and unsatisfactory in 5 (1%) cases. Blind tracheal intubation through the intubating laryngeal mask was possible in 481 (96.2%) cases within three attempts. Intubation was successful at the first attempt in 399 (79.8%) cases, at the second attempt in 62 (12.4%) cases and at the third attempt in 20 (4%) cases. The tracheas of 19 (3.8%) patients were not successfully intubated within the three attempts. Ventilation via the intubating laryngeal mask was described as unsatisfactory during two of these cases but oxygenation remained satisfactory in spite of this. Seventeen of the 19 failures occurred during the individual operator's first 20 attempts. The intubating laryngeal mask provides a successful method for blind tracheal intubation in a large proportion of cases and appears to be superior to the standard laryngeal mask airway for this purpose. The intubating laryngeal mask may be of use when tracheal intubation has failed using conventional methods.     

The reinforced laryngeal mask in paediatric outpatient dental surgery

One hundred and twenty ASA I and II grade children aged 2-9 years scheduled for outpatient dental extractions under general anaesthesia were studied. They were allocated randomly to one of three groups for airway management: group R had anaesthesia with a reinforced laryngeal mask airway, group L with a standard laryngeal mask airway and group N with a nasal mask. Anaesthesia was induced in all children using halothane in 50% nitrous oxide with oxygen and maintained on halothane in 67% nitrous oxide with oxygen. An Ayre's T-piece with Jackson-Rees modification was used. The incidence of airway obstruction was significantly lower and surgical access significantly better with the reinforced laryngeal mask airway when compared with the standard laryngeal mask airway. However, the reinforced laryngeal mask airway was significantly more difficult to insert when compared with the standard laryngeal mask airway. On comparing the reinforced laryngeal mask airway with the nasal mask, there were significantly fewer episodes of airway obstruction, better oxygen saturation, less increase in heart rate and fewer arrhythmias in the reinforced laryngeal mask airway group. Total time for the procedures was the same for all three groups. Thus, the reinforced laryngeal mask airway was found to be a favourable alternative to the standard laryngeal mask airway and nasal mask for paediatric outpatient dental extractions.     

The effect of introducing fibreoptic bronchoscopes on gas flow in laryngeal masks and tracheal tubes

The laryngeal mask airway, reinforced laryngeal mask airway and tracheal tube were studied to determine (1) flow resistance during simulated inspiration and (2) the maximum size of fibreoptic scope which can he passed down the lumen at clinically useful ventilatory settings. In addition, the flow resistance imposed by the mask aperature bars was quantified. The laryngeal mask airway can accommodate a larger fibrescope than the corresponding sizes of reinforced laryngeal mask airway or tracheal tube. Mean (range)flow resistance was 2.3 (1.7-35) times higher with the reinforced laryngeal mask airway compared to the laryngeal mask airway, 2.1 (1.2-4.2) times higher with the tracheal tube compared with the laryngeal mask airway and 1.2 (0.7-1.8) times lower with the tracheal compared with the reinforced laryngeal mask airway. Removal of the mask aperture bars resulted in a mean decrease in flow resistance of 3.6%. Our data have shown that the laryngeal mask airway can accommodate a larger fibrescope than either the reinforced laryngeal mask airway or tracheal tube at clinically useful ventilatory settings and that the current recommendations for maximum size of fibrescope should be revised.     

Use of the intubating laryngeal mask in children: an evaluation using video-endoscopic monitoring

BACKGROUND AND OBJECTIVE: The intubating laryngeal mask is designed to act as a ventilatory device and as an aid to blind tracheal intubation in adults. The aim of this study was to evaluate the efficacy of the intubating laryngeal mask for ventilation of the lungs and tracheal intubation in children using video-endoscopic control. METHODS: The handling and efficacy of the size 3 intubating laryngeal mask for tracheal intubation in 80 children weighing > or = 25 kg were assessed under video-endoscopic control. Ease of intubating laryngeal mask insertion, adequacy of lung ventilation through the intubating laryngeal mask and airway sealing pressures were recorded. Tracheal intubation was performed blindly by the intubator, while the supervisor observed the procedure on the video display. If blind intubation failed at the first attempt, the monitor view was used to guide the tracheal tube into the trachea. The success rate and time required for successfully placing the tracheal tube were recorded. RESULTS: Insertion of the intubating laryngeal mask was easy in all children. Lung ventilation through the intubating laryngeal mask was uniformly excellent. Blind tracheal intubation at the first attempt was successful in 53 children (66%) within 18.8 +/- 4.1 s. Twenty-four of the 27 failed blind intubation attempts were successfully intubated with video-endoscopic guidance within 28.6 +/- 9.4 s. Two children required replacing the intubating laryngeal mask, one child had to be intubated conventionally. CONCLUSIONS: The size 3 intubating laryngeal mask provides an airway that is easy to establish in children > or = 25 kg with excellent ventilation conditions and allows blind tracheal intubation at the first attempt with a high success rate. Endoscopic monitoring improves its safety and intubation success rate.     

Nasal fibreoptic tracheal intubation in anaesthetised patients breathing via a modified laryngeal mask airway

A modified laryngeal mask airway was used to facilitate nasotracheal intubation with a fibreoptic laryngoscope. A size 4 laryngeal mask airway was modified by creating a defect at the base of the stem and removing the bars to allow passage of the fibreoptic laryngoscope from the nasopharynx to the larynx. The laryngeal mask airway cuff was split and the cut edges were sealed with silicone. This design allowed the cuff to function normally and allowed removal of the split laryngeal mask airway after the tracheal tube had been 'railroaded' into place. Thirty-four patients were studied. The split laryngeal mask airway was easily inserted with satisfactory airway maintenance in 32 patients. Nasal airway endoscopy and laryngoscopy were successfully achieved with the split laryngeal mask airway in place in 31 of 32 patients. Railroading the tracheal tube over the fibreoptic laryngoscope with the split laryngeal mask airway in place was successful in all 31 of these patients. This prototype split laryngeal mask airway allows good airway maintenance while fibreoptic nasotracheal intubation is performed.     

The laryngeal mask airway as an aid to training in fibreoptic nasotracheal endoscopy

We have investigated the extent to which the laryngeal mask airway, when used as an aid to fibreoptic nasotracheal video-endoscopy training, could reduce endoscopy apnoeic time in anaesthetised, paralysed oral surgery patients. Twenty anaesthetic trainees were randomly allocated to the laryngeal mask airway or control group. Laryngeal mask airway group endoscopies were performed in three stages following insertion of the laryngeal mask airway; stage 1: nasendoscopy, with the lungs ventilated automatically through the laryngeal mask airway; stage 2: removal of the laryngeal mask airway; stage 3: pharyngoscopy, larygoscopy and tracheoscopy. Control group endoscopies were performed conventionally, in one stage. Each trainee performed five nasotracheal intubations. Though total endoscopy time in the laryngeal mask airway group (stage 1 + stage 2 + stage 3 times) was significantly longer (average 136 s vs. 108 s), apnoeic time (stage 2 + stage 3 times) was significantly shorter (average 59 s vs. 108 s) than endoscopy time in the control group. This application of the laryngeal mask airway may have a useful role to play in ensuring patient safety during early fibreoptic training.     

Evaluation of four airway training manikins as simulators for inserting the LMA Classic*

Airway manikins have traditionally been used for teaching mask ventilation and tracheal intubation. There is an increasing need to use manikins for training in procedures such as insertion of the laryngeal mask airway. We have assessed four new airway training manikins (latest versions of the Airway Trainer (Laerdal, Norway), Airway Management Trainer (Ambu, UK), 'Bill 1' (VBM, Germany) and Airsim (Trucorp, Ireland)) as simulators for insertion of the LMA Classic laryngeal mask airway. Twenty volunteer anaesthetists inserted a size-4 laryngeal mask airway five times into each of the four manikins, in random order. Each insertion was assessed using objective and subjective tests. Subjective assessment varied widely but overall assessment indicated that the Airway Management Trainer was the poorest simulator for insertion of the laryngeal mask airway. The 'Bill 1' and Airsim manikins performed best as simulators for insertion of the laryngeal mask airway, although realistic ventilation with 'Bill 1' was not possible.     

BlockBuster喉罩在泌尿外科日间手术中的应用

目的观察BlockBuster喉罩用于泌尿外科日间手术的临床效果。方法选择泌尿外科日间手术患者42例,男38例,女4例,年龄65~83岁,ASAⅠ~Ⅲ级,随机分为BlockBuster喉罩组(B组)和Proseal喉罩组(P组),每组21例。麻醉诱导后根据患者体重选择适当型号的喉罩,B组置入BlockBuster喉罩,P组置入Proseal喉罩;记录两组喉罩一次置入成功率、喉罩置入后15 min PETCO2和Ppeak、经喉罩插管次数或喉罩换管次数、胃反流误吸和拔出喉罩后声嘶、咽痛等并发症的发生情况。结果 B组喉罩一次置入成功率明显高于P组,插管或换管率明显低于P组(P0.05);B组喉罩置入后15min Ppeak明显低于P组(P0.05);B组声嘶发生率明显低于P组(P0.05)。结论与Proseal喉罩比较,BlockBuster喉罩在泌尿外科日间手术中可提供良好的声门上气道管理,同时增加声门下应急气管插管通道,反流误吸发生风险小且术后声嘶、咽痛等并发症少,有效提高泌尿外科日间手术术后患者恢复质量。     

局部利多卡因凝胶与静脉注射利多卡因在喉罩应用中的比较研究

目的探讨在喉罩使用过程中局部利多卡因凝胶与静脉注射利多卡因对维持血流动力学的稳定性是否有相同效应。方法选择2011年6月～2012年10月择期全麻下腹腔镜胆囊切除术48例,随机分为3组,每组16例。T组（局部给药组）,2％利多卡因凝胶涂抹于喉罩罩杯的双面,同时静脉注射生理盐水10ml;1组（静脉给药组）,普通水溶性润滑剂涂抹于喉罩罩杯的双面,同时2％利多卡因1．5mg／kg生理盐水稀释至10ml静脉注射;C组（对照组）,普通水溶性润滑剂涂抹于喉罩罩杯的双面,同时生理盐水10ml静脉注射。记录喉罩置入前,置入即刻,置入后1、3、5min,以及拔除喉罩前1min,拔除即刻,拔除后1、3、5min的平均动脉压（MAP）、心率（HR）,记录拔除喉罩前后并发症。结果3组置入和拔出喉罩时MAP、HR无明显变化（P〉0．05）。T组和I组MAP在喉罩置入后1min和拔出即刻、1min、3min、5min明显低于C组（P〈0．05）。拔除喉罩后3组均无喉痉挛和吞咽困难发生,咽痛、干呕并发症发生率3组差异无显著性（P〉0．05）。结论局部应用利多卡因凝胶与静脉注射利多卡因在喉罩使用过程中对维持血流动力学的稳定性具有相同效应。     

Protein cross-contamination during batch cleaning and autoclaving of the ProSeal laryngeal mask airway

We tested the hypothesis that protein cross-contamination occurs during batch cleaning and autoclaving of a reusable extraglottic airway device, the ProSeal laryngeal mask airway. At the end of each day for 10 days, nine laryngeal mask airways that had been used for non-intra-oral surgery were cleaned and autoclaved alongside a new unused laryngeal mask airway. In addition, a new unused laryngeal mask airway underwent the same cleaning and autoclaving procedures in isolation. Protein staining was more frequently detected on the unused laryngeal mask airways that were processed by batch rather than in isolation (p < 0.01). Protein staining was detected on all unused laryngeal mask airways that were processed by batch, but none on those processed in isolation. Protein staining was more severe with the used compared with the unused laryngeal mask airways (p < 0.001). We conclude that protein cross-contamination of the laryngeal mask airway occurs during batch cleaning and autoclaving and recommend that reusable airway devices are cleaned in isolation.     

A comparison of the intubating and standard laryngeal mask airways for airway management by inexperienced personnel

Twenty-four inexperienced participants were timed inserting the intubating laryngeal mask airway and the laryngeal mask airway in 75 anaesthetised subjects. Adequacy of ventilation was assessed on a three-point scale. The pressure at which a leak first developed around the device's cuff was also measured. There was no significant difference in insertion time or the likelihood of achieving adequate ventilation between devices. However, the intubating laryngeal mask airway was better at providing adequate ventilation without audible leak (58/75 (77%) vs. 42/75 (56%); p = 0.009). The median (range [IQR]) pressure at which an audible leak developed was higher for the intubating laryngeal mask airway, 34.5 (14-40 [29-40]) cmH2O, than for the laryngeal mask airway, 27.5 (14-40 [22-33]) cmH2O (p < 0.001). The intubating laryngeal mask airway is worthy of further consideration as a tool for emergency airway management for inexperienced personnel.     

COMPARISON OF THE USE OF THE LARYNGEAL MASK AND FACE MASK BY INEXPERIENCED PERSONNEL

Ten junior doctors with no postgraduate anaesthetic experienceattempted to ventilate the lungs of 50 anaesthetized patients,using either a laryngeal mask or a Guedel airway and face mask.Success was defined as the production of two successive tidalvolumes exceeding 800 ml within 40 s. The failure rate was significantlygreater using the laryngeal mask compared with the face mask(P < 0.05) and the average time was significantly longerwith the laryngeal mask than with the face mask (P < 0.01). The results from this investigation suggest the laryngealmask airway cannot be recommended as a resuscitation devicefor use by inexperienced operators.     

Use of a larynyngeal mask airway during aortic valve replacement

We report the elective use of a laryngeal mask airway during cardiac surgery for congenital tracheal stenosis. A 53-year-old woman with severe aortic valve stenosis was scheduled for aortic valve replacement. During anesthesia induction, the anesthesiologists attempted conventional intubation but failed. Fiberoptic tracheal examination and computed tomography showed a tracheal stenosis with 5 mm minimal diameter. A laryngeal mask airway was used at the patient's rescheduled surgery. The laryngeal mask airway use did not lead any surgical complication. We concluded that the laryngeal mask airway may be considered as an alternative to conventional intubation in patients with tracheal stenosis.     

Use of a larynyngeal mask airway during aortic valve replacement

We report the elective use of a laryngeal mask airway during cardiac surgery for congenital tracheal stenosis. A 53-year-old woman with severe aortic valve stenosis was scheduled for aortic valve replacement. During anesthesia induction, the anesthesiologists attempted conventional intubation but failed. Fiberoptic tracheal examination and computed tomography showed a tracheal stenosis with 5 mm minimal diameter. A laryngeal mask airway was used at the patient's rescheduled surgery. The laryngeal mask airway use did not lead any surgical complication. We concluded that the laryngeal mask airway may be considered as an alternative to conventional intubation in patients with tracheal stenosis.     

The laryngeal mask as an antipollution device

Anaesthetic pollution is still a problem and recent UK Control of Substances Hazardous to Health (COSHH) recommendations require employers to attempt to control the risk. Fifteen day-case urology operating lists were studied to compare the level of nitrous oxide exposure using face mask or laryngeal mask anaesthesia. Nitrous oxide was avoided in one group until the laryngeal mask was inserted. The use of the laryngeal mask airway showed a significant reduction in the level of pollution, such that recent COSHH recommendations were attained. However, (US) NIOSH levels were only reliably attained by avoiding nitrous oxide until the laryngeal mask was inserted. The laryngeal mask was therefore shown to be a reliable antipollution device.     

Stability of the LMA-ProSeal and standard laryngeal mask airway in different head and neck positions: a randomized crossover study

BACKGROUND AND OBJECTIVE: The LMA-ProSeal laryngeal mask airway is a new laryngeal mask airway with a modified cuff and drainage tube. We compared oropharyngeal leak pressure, intracuff pressure and anatomical position (assessed fibreoptically) for the Size 5 LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway in different head-neck positions and using different intracuff inflation volumes. METHODS: Thirty paralysed anaesthetized adult male patients were studied. The LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway were inserted into each patient in random order. The oropharyngeal leak pressure, intracuff pressure, and anatomical position of the airway tube and drainage tube (LMA-ProSeal laryngeal mask airway only) were documented in four head and neck positions (neutral first, then flexion, extension and rotation in random order), and at 0-40 mL cuff volumes in the neutral position in 10 mL increments. RESULTS: Compared with the neutral position, the oropharyngeal leak pressure for both the LMA-ProSeal laryngeal mask airway and the classic laryngeal mask airway was higher in flexion and rotation (all P < or = 0.02), but lower in extension (all P < or = 0.01). Changes in head-neck position did not alter the anatomical position of the airway tube or the drainage tube. The oropharyngeal leak pressure was always higher for the LMA-ProSeal laryngeal mask airway (all P < or = 0.005) and anatomical position better for the classic laryngeal mask airway (all P < or = 0.04). CONCLUSIONS: The anatomical position of the LMA-ProSeal and the classic laryngeal mask airway is stable in different head-neck positions, but head-neck flexion and rotation are associated with an increase, and head-neck extension a decrease, in oropharyngeal leak pressure and intracuff pressure. The Size 5 LMA-ProSeal laryngeal mask airway is capable of forming a more effective seal than the Size 5 classic laryngeal mask airway in males.